Solution-Processed Visible-Blind Ultraviolet Photodetectors with Nanosecond Response Time and High Detectivity

Ultrafast, high-sensitivity, visible-blind ultraviolet (UV) photodetectors are crucial for practical applications, including: optical communication, environmental ozone hole monitoring, and combustion and chemical detection. However, commercial visible-blind UV photodetectors based on traditional inorganic semiconductor materials involve expensive production processes, while the currently solution-processed detectors still suffer from issues of low sensitivity or slow response speed. Herein, high-performance visible-blind UV photodetectors with simultaneously ultrafast response speed and high detectivity are achieved from solution-processed micrometer-thick methylammonium lead trichloride perovskite thin single crystals, grown in high quality with smooth surfaces by judiciously designing the substrate's wettability. The as-fabricated UV photodetectors exhibit a low noise of 6.5 fA Hz−1/2, a low detection limit of 8.5 pW cm−2, and high specific detectivity of ≈6 × 1012 Jones. A fast response time of 15 ns and a large bandwidth of 25 MHz are obtained when decreasing the crystal thickness to 1 µm. The nanosecond response speed is several orders of magnitude faster than the best ever reported solution-processed visible-blind UV photodetectors and is comparable to reported UV photodetectors based on traditional (high-temperature processed) inorganic semiconductors. The high performance combined with low-cost fabrication makes these visible-blind UV photodetectors highly attractive for applications in optical communication and ultrafast detection.